 # Motor & worm gear calculations

Dear all,

Here i wanted to go from basic. I need basic steps to calculate or choose proper wormgear & motor for solar tracking application.

If someone can guide me necessary formula & parameter required to calculate the worm gear box . i have already discuss this topic earlier but not posted in in right thread & i didn't get response

http://www.sunflowerenergyinc.com/Slewing_Drive_-_032511_-_REV.03.pdf

calculation formula required: 1) torque Vs speed relation for motor & worm gear 2) torque Vs load for motor & worm gear 3) Input power & output power for motor & worm gear 4)turns ratio relationship with motor & worm gear.

I know these are basic question but some tracker design taking kinematic calculation for this. http://www.roymech.co.uk/Useful_Tables/Drive/Worm_Gears.html

so if some one can guide with proper resource it will be more help full.

AMPS-N: choose proper wormgear & motor for solar tracking application.

I would use the brute-force method. Buy a big motor! If that won't move the device, buy a bigger one.

What about a used car windscreen wiper motor?

...R

I have these realtionship with worm gear Box. I need standard method or assumption to choose to calculate motor & specification.

efficiency= (output Power of Worm gear/ Input Power of WormGear) = Po/Pinput

Output power =P0=(2*pi*Outputspeed*outputtorque)/60

Output power in Kw Outputspeed in rev/min outputtorque in Nm

Input power = Pinput=(2*pi*Input speed*Input torque)/60

Output power in Kw Input speed in rev/min Input torque in Nm

Net Torque= Toutput+TInput+Tholding =0

These are basic equation followed usually

In order to drive 250Kw plant ; assume 15kw per row I have 16 rows with 1 column.

Worm gear has to Drive 16 rows with coupling with single column item

each panel weighs 20Kg ; 60 panel per row-> 60*20kg=1200Kg Each row structural weight around = 700Kg

Net weight alone = 1900Kg per Row

so load on worm gear might be 1900*16=30400

Now how can i consider above assumption for motor drive selection

You're out by a factor of 1000!

power = torque * angular-velocity

torque in Nm angular-velocity in rad/sec power in watts (NOT kW)

AMPS-N:
calculation formula required:

1. torque Vs speed relation for motor & worm gear

There isn’t one, torque and speed are independent for a DC motor,
the voltage or PWM duty cycle determines the speed, the torque is

When I say there isn’t one, I mean the load sets this relationship, not
the motor/gear

1. torque Vs load for motor & worm gear

1. Input power & output power for motor & worm gear

This has been covered, you can perhaps expect ~50% efficiency for a worm
gear due to the high friction levels

4)turns ratio relationship with motor & worm gear.

What turns? This isn’t a transformer. Tooth ratio maybe, most
(but not all) worm gears are single tooth (single helix), so the ratio
is just the number of teeth in the spur gear.

Example working:

You want 300Nm torque at 0.1 rad/sec (1 rpm) via a 60:1 worm
reduction gear.

Input torque = 300/60 = 5Nm, input angular velocity = 0.1*60 = 6 rad/s (60rpm)
BUT that assumes 100% efficiency, so actually more like 10Nm torque needed.

In this example you clear need more reduction gearing since most motors are
1000’s of rpm and < 1Nm

10Nm at 6 rad/s = 60 watts mechanical, ie about 80 to 100W electrical to the
motor terminals.

BTW 300Nm is a stupidly large value, this is only an example of the maths.